Manufacture of bis-(b-hydroxyalkyl-) polysulfides



United States atent O MANUFACTURE OF BIS-(B-HYDROXYALKYL-) POLYSULFIDES Georg Spielberger, Leverkusen-Bayerwerk, and Wilhelm Krey, Krefeld-Uerdingen, Germany, assignors to Farbenfabriken Bayer Aktiengesellschaft, Leverknsen, Germany, a corporation of Germany No Drawing. Application Much 18, 1953, Sean No. 343,246

Claims priority, application Germany March 22, 1952 5 Claims. (Cl. 260-608) This invention relates to bis-(B-hydroxyalkyl-)polysulfides and is more particularly concerned with an improved process for preparing bis-(5-hydroxyalkyl-)polysulfides.

It is well known to produce bis-(B-hydroxyalkyl-)polysulfides by reacting alkylene chlorhydrins with alkalior earth-alkali polysulfides in an aqueous medium. The bis- (e-hydroxyalkyb)polysulfides obtained in the reaction separate from the resulting alkali chlorideor earth-alkali chloride solution in the form of viscous oils, the degree of the separation depending upon the concentration of the aqueous solution. It is, therefore, necessary to start from very concentrated alkylene chlorhydrin solutions which cannot directly be prepared from the corresponding olefin and chlorine in the presence of water, but only by reacting the corresponding alkylene oxide with hydrochloric acid.

If, on the other hand, the quantity of the solvent (water), used in the known method, is reduced to such an extent that the alkalior earth-alkali chloride formed as a byproduct partially crystallizes out, a further difiiculty arises, viz. the separation of the precipitated inorganic salt from the viscous reaction product, an operation involving loss of product.

It is an object of the present invention to provide an improved process for preparing bis-(B-hydroxyalkyl-)polysulfides. Another object is to provide a process for the production of bis-(B-hydroxyalkyl-)polysulfides, whereby good yields are obtained. Further objects will appear as the specification proceeds.

These objects are attained in accordance with the present invention by reacting a l,2-alkylene oxide with an alkalior earth-alkali polysnlfide and neutralizing the base liberated in the reaction in such a manner that the inorganic polysulfide serving as one of the reactants is not decomposed to hydrogen sulfide and sulfur.

This neutralization can be effected by adding to the reaction mixture the calculated amount of any suitable alkali-binding substance, such as carbon dioxide, sodium bicarbonate, buffer solutions containing acetates, borates, phosphates and the like, and mineral acids if introduced carefully enough to preclude a decomposition of the alkalior earth-alkali polysulfide.

A preferred method of carrying out our invention comprises reacting l,2-alkylene oxides with sodium polysulfide and neutralizing the sodium hydroxide liberated in the reaction with carbon dioxide at the rate as it is formed. When ethylene oxide is used as an alkylene oxide the reaction occurring in accordance with this embodiment of our invention may be written as follows:

Nays, 20277011: 001+ H2O Sz(CH2CH2OH)2 NazCOi By simultaneously introducing stoichiometric proportions of alkylene oxide and carbon dioxide into the solution of sodium polysulfide over-acidifying can be avoided. A

further advantage of this method resides in the fact that sodium carbonate is much more soluble in water than "ice sodium chloride formed in the known process, so that very concentrated aqueous solutions can be handled without any difiiculty arising from precipitated sodium chloride.

1,2-alkylene oxides suitable for the process of our invention include ethylene oxide, propylene oxide, 3-hydroxypropylene-oxide-l,2 and the like.

The temperatures which have been found most satisfactory for the reaction according to our invention range from about 30 to about 90 C., but the method may be carried out at higher or lower temperatures, if desired. The alkylene oxide is introduced into the reaction mix ture either in the gaseous or in the liquid form. In general, the reaction occurs very readily, so that superatmospheric pressure is unnecessary. The alkali-binding substance is suitably added along with the alkylene oxide as stated hereinabove. If carbon dioxide is used as the alkali-binding substance one mol is introduced for two mols of alkylene oxide (see the above equation). Carbon dioxide and ethylene oxide, when employed as reactants, may be mixed in this ratio before being added to the solution of the inorganic polysulfide.

The process in accordance with the invention makes it possible to obtain good yields of bis-(fi-hydroxyalkyb) polysulfides. This finding is very surprising as alkylene oxides are readily hydrolyzed in an aqueous alkaline medium and are apt to form polyethers. However, these side-reactions do not occur to an appreciable extent in our process.

The bis-(,B-hydroxyalkyl-)polysulfides which have become easily obtainable by the present invention are mixtures of individual compounds containing a different number of sulfur atoms, the degree of sulfuration depending upon the proportion of sulfur present in the inorganic polysulfide employed as a starting material.

The bis-(B-hydroxyalkyb)polysulfides prepared in accordance with this invention are useful as intermediates for the manufacture of dyes, pharmaceuticals and agricultural chemicals.

The following examples serve to illustrate our invention without in any way limiting it:

Example 1 A mixture of 2 parts by volume of ethylene oxide and 1 part by volume of carbon dioxide is introduced into a solution of 260 parts by Weight of 60 percent sodium sulfide and 70 parts by weight of sulfur in 500 parts by weight of water until the aqueous layer has become almost colorless. This stage is arrived at after about 176 parts by weight of ethylene oxide and 88 parts by weight of carbon dioxide have been taken up. During the introduction of the gases the mixture is vigorously agitated and the temperature is held in the range from 50 to C. by cooling. On introduction of the gases the mixture is kept for some time at the reaction temperature. The reaction mixture is worked up by separating the layers at moderately elevated temperature. On cooling sodium carbonate-decahydrate (NazCOalOHzO) precipitates. The mother lye retains a small proportion of bis-(hydroxyethyl-)polysulfide and can be used for the next run.

The reddish-yellow oily layer (355 parts by weight) comprises the bis-(hydroxyethyl-)polysulfide formed in the reaction.

Sulfur content: 33 percent. Refractive index:

Example 2 26 kilograms of ethylene oxide and 13 kilograms of carbon dioxide are added with stirring at a temperature of 40 to 50 C. and over a period of 14 hours to a solution of 10 kilograms of sulfur and 70 kilograms of sodium sulfide percent) in liters of water. On separation of the layers 51 kilograms of crude bis-.(hydroxyethyl-) polysulfide are obtained. A' further quantity of 3 kilograms of bis-(hydroxyethyl-)polysulfide may be obtained by extractingthe aqueous layer with butanol'. On drying the bis;(hydroxyethyl-)polysulfide contains:42l8 percentof sulfur. By catalytic hydrogenation of the polysulfide in the presence of a suitable catalyst percent of monothioglycol' (based on ethylene oxide consumed) is obtained.

Example 3 rams of ethylene oxide are introduced with stirring at 3O 50 C; over aperiod of 6 hours int o asolutioni of 240 grams of crystalline sodium 's ulfide' percent) and 36' grams of sulfur in' ccm; of Water. Simultaneously and uniformly 450 grams of 20 percent-sulfuric acid" are added dropwise at a vigorously" agitated point'of the reaction mixture below'the surface. Crude bis-(hydro'xy ethyl-)polysulfide is ohtainedyielding on catalytic hydrogenation 70 percent of the theoretical (based on ethylene oxide" consumed) of thioglycoli Weclaim: v 7 7 l. A-pr'o'ces's' for preparing bis-(fl hydroxyalkympolysulfides which comprises reacting, in the presence of water, 1,2-alkylene oxides with alkali metal polysulfides while simultaneously adding an alkali-binding substance to neutralize the liberated alkali-metal hydroxide as it is formed. t

2. The process of claim l-wherei1r the neutralization is eifected with carbon dioxide.

3. A process for preparingbis-(,B-hydroxyalkylfipolysulfides which comprises introducing s'toichiometric amounts of carbon dioxide and of a l,2-alkylene oxide into an aqueous solution ofanalkali-metal' polysulfide.

4. A process for preparing bis-(p-hydroxyalkylfipolysulfides which comprises" introducing stoichiometric amounts of carbon dioxide and a 1.2-alkylene oxide into an aqueous solution ofsodium'polysulfide.

5. The process of claim 4 wherein, instead of sodium polysulfide, a mixture of sodium monosulfide and sulfur is employed;

References Cited in Y the file of" this patent UNITED STATES PATENTS 2,257,290 Voorhees -e; Sept. 30, 19 4 1,- 2,s27;37s' Bertozzi Oct. 24, 1950 

1. A PROCESS FOR PREPARING BIS-(BHYDROXYALKYL-E POLYSULFIDES WHICH COMPRISES REACTING, IN THE PRESENCE OF WATER, 1,2-ALKYLENE OXIDES WITH ALKALI METAL POLYSULFIDES WHILE SIMULTANEOUSLY ADDING AN ALKALI-BINDING SUBSTANCE TO NEUTRALIZE THE LIBERATED ALKALI-METAL HYDROXIDE AS IT IS FORMED. 